The effects of isouramil on erythrocyte mechanics: implications for favism.

Isouramil is one of the two aglycones derived from broad beans (Vicia faba) with the capacity to autoxidize and generate hydrogen peroxide. During its incubation with erythrocytes in vitro, it causes a marked decrease in cellular deformability at low shear forces, as measured by cone plate viscometry. At the same time the membrane shear modulus of elasticity, as determined by the dimensions of pressure induced pseudopods (PIPs), is increased. These experiments suggest that alterations in the mechanical properties of erythrocyte membranes may be the basis for changes in cellular deformability and hence, erythrocyte sequestration in G-6PD deficient cells exposed to peroxide-generating agents, such as isouramil.